Ronald Reagan put an expression into the everyday vernacular when discussing nuclear disarmament agreements with the old USSR: “Trust, but verify.” I found that to be sage advice when dealing with our teenagers: trust them, but God help them if we as their parents ever found we couldn’t verify the facts as events unwound. It’s also good advice in the glass biz.
We see comments on architecturals and shop drawings all the time about details being “similar.” There’s never a discussion or explanation about just how similar, or more importantly, how dis-similar the detail may be at the location it’s referenced. It’s a shortcut taken to draw one less detail.
Or in dealing with unitized walls, when is “opposite hand” not really opposite hand? When mullions are started out the male on the left, the female on the right, does the author of the “opposite hand” comment mean to turn the male/female mullions around also? I have seen where the detail was opposite, such as a jamb-to-brick transition, but the split mullions always stay male/left, female/right. So is it really opposite-hand or not? I’ll leave those discussions for the coffee machine or water cooler philosophy sessions.
My all=time favorite remains “Verify In Field.” I’ve always loved to see that on a set of shop drawings, especially on new construction. Let’s remove renovation or remodeling projects from this discussion. Immediately. Someone better check the dimensions of the existing openings before the windows are built. Whether that happens before shop drawings are even prepared or prior to actual metal fabrication, it’s still required. So someone’s going to have to get out in the field and check the openings.
To not do that runs the risk that the windows, if made from approved shop drawing dimensions, are going to be too big or too small when they arrive on-site. And, something is going to need to be revised, and in all likelihood, it won’t be the opening. Further, not only will the metal have to be changed, glass sizes also might be adversely affected. Not a pretty thought when it comes to meeting schedules. “VIF” in remodel/retrofit is an absolute necessity.
But when “VIF” shows up on new construction shop drawings, I wonder if someone understands the process and/or sequence of building or understands the impact that has on schedule and cost.
First, the general contractors are going to be all over this because of schedule. If they build the openings, then wait for the dimensions to be taken before the windows can be built, why submit elevations with shop drawings? That linear sequence adds weeks to schedules.
Second, in order to meet original schedule commitments that were made with the glazing subcontractor or metal fabricator’s input, the metal suppliers aren’t given the time to wait on the openings to be built.
The work-around for this is quite simple, and it may be the glazing sub or the metal fabricator that can drive this. What has to be determined prior to starting the work creating the openings is a preconstruction meeting where the tolerances of the openings are discussed and determined BEFORE that work commences. I could argue this meeting should be held not prior to construction, but prior to window shop drawings beginning. All parties affected, from architect to general contractor and related trades could openly and directly address all the issues that go into the consideration of what tolerances the openings will have.
From the opening trades’ point of view, they have rough opening dimensions they can get from the architecturals, their own shop drawings, or the window/curtainwall shops. And setting the tolerances then and there, with the architect’s blessing (usually the stick in the proverbial mud, they want them as small as possible, the sub is going to push for “bigger the better”), everyone’s on the same page.
The glazing sub and the metal manufacturer have to account for not only the opening tolerances, but also other factors including sealant capacity, expected building movements for seismic and/or live load deflection, window expansion and contraction, and frame manufacturing and erection tolerances. These factors all contribute to the final joint size between window/curtainwall and surround.
The “preconstruction meeting” moved to a “pre-shop drawings” meeting permits a setting where all affected parties are in the room at the same time, which allows for an open discussion of the issues and enables issues to get recognized and resolved before one piece of metal has been cut. It sure beats having the discussion when the glazier is standing in front of an opening, window leaning into it, which just so happens not to fit.
After this meeting, the window manufacturer can then submit the shops with dimensions shown for the windows that will ALWAYS fit the opening, regardless of whether the openings are too big or too small from nominal. The onus is put on the opening subcontractor to frame the openings per the agreed-upon tolerances.
That’s not to say this is foolproof. Someone will not hold up their end: an opening too small, a window too big. Mistakes happen. But, the rules will have been set, and the blame will clearly fall to the party at fault, with no chance to escape responsibility. But only IF and WHEN everybody’s signed off on this. Including the architect and GC in this discussion is of PARAMOUNT performance. The GCs will want to facilitate the discussion since it’s their responsibility to coordinate the work. When they see installation of windows goes smoother, they’ll be converts forevermore.
“VIF” is a flag that says that whoever put that mark on the drawings recognizes this dilemma, and thinks it’s best solved after the openings are built. Please, can’t we all just get along, and play nice up front, do a little extra legwork, lay some ground rules prior to ANY activity taking place? In the end, wouldn’t all our lives be simpler? Schedules would be shrunk, unknowns taken out of the equation, and everyone doing what they’re supposed to. To this writer, the KISS principle is in effect. I’m not the brightest lite in the window, but I am not stupid enough EVER to fall for VIF on new construction drawings. EVER.
You can trust all you want that the windows will fit when they get to the jobsite, but having this meeting verifies everyone has bought in, and mistakes aside, a proper installation will follow.